Small electronic components, including amplifiers, filters, transducers and the like, are employed in a number of devices, particularly in radio frequency (RF) wireless communications, for example. Conventionally, the electronic components are combined in circuit packages and covered with external shields to form discrete shielded packages, referred to as “product modules” or “modules.” Such module may be a full semiconductor chipset package including a printed circuit board (PCB) and one or more surface mount technology (SMT) components, such as the power amplifiers, filters and/or transducers. For wireless communications, for example, the SMT components may be molded together within an area of the module, typically having dimensions on the order of square millimeters, and work together at frequencies in gigahertz (GHz) ranges (e.g., 1.5 GHz and above). Over time and in response to demand, modules have been becoming smaller and/or incorporating multi-bands. Accordingly, the number of the interacting SMT components within a particular module may increase, while attempts are still being made to minimize the area of the module. This results in a higher chance of noise among the SMT components in close proximity, such as electromagnetic interference (EMI) caused by electromagnetic radiation emitted from the SMT components.
The external shields are generally shield layers that cover top and sidewalls of the modules, and provide protection against externally generated electromagnetic radiation (“external electromagnetic radiation”), as well as and environmental stress, such as temperature, humidity, and physical impact, for example. In order to provide protection against the external electromagnetic radiation, the external shields are formed of electrically conductive material, typically metal. The bottoms of the modules are typically not shielded by external shield layers, although the substrate, the ground layer, external connecting pins protruding from the PCB, and/or various electronic components, transmission lines and other circuitry within the PCB generally may provide some external shielding from external electromagnetic radiation. The external shield layers together with the bottom shielding together provide a “global shield” for the module.
One drawback of an external shield is that it provides no shielding of individual electronic components from internally generated electromagnetic radiation (“internal electromagnetic radiation”) produced by other electronic components within the module, causing EMI, such as capacitive and inductive coupling and cross-talk. Indeed, the external shield, in some cases, may aggravate the EMI by reflecting the internal electromagnetic radiation back toward the electronic components within the module.
Various attempts to reduce internal noise within the module include internal EMI shielding, separating the SMT components. However, conventional internal shields may be ineffective and/or difficult and time-consuming to fabricate. Accordingly, what is needed is enhanced internal shielding and a more efficient process for fabricating internal shields, such as metal wire fences, in terms of process duration, cost, and less contact error between the wire or other metal forming the shields and the surface of the PCB, for example.